The rack configuration problem is defined as follows. We are given a set of boxes, a set of racks (e.g., bookcase-like structures), and a set of places to put the racks. Some or all of the boxes may have one or more connections or links to other boxes. The racks may be extant, or may merely be a set of available rack types that could be used, perhaps with limits on the number available. The placement of boxes in racks is constrained by physical limits such as their size (a rack holds only a certain amount or number of boxes), power (a rack can only support a certain power drain from the boxes it holds), and so forth. The objective is to decide where to position the boxes into the racks and how to place the racks themselves, subject to these conditions, in such a way as to minimize various objectives, such as the number or cost of the racks used, the total length of the links between racks, or the number of links that cross rack boundaries.
In the most general case, a rack can be any container of boxes, a box can be any entity that can be placed in a rack.
A particular example of interest occurs when the boxes are computer or network components, such as network devices, computers, storage devices, hubs, switches, routers, displays, keyboards, storage area network (SAN) devices, fans, air ducts, telecommunication devices, telephone equipment such as telephones, computer system components, Internet data center devices, local area network (LAN) devices, disk array components, tape library devices, UNIX system components, WINDOWS system components, I/O subsystems, I/O and storage controllers, power supplies, cooling units, and other electronic devices. In what follows, the terms “box”, “device”, and “component” will be used to encompass all of these kinds of boxes, as well as any other item that could be placed in a rack subject to constraints such as the rack's capacity.
In the computer network case, the racks are often standard computer-system mounting racks, which typically hold boxes that are designed with one or two standard widths and a range of heights, often expressed in terms of “units”, but other types of rack are possible and relevant for this problem. Again, in what follows, the term “rack” will be used to include all of these possibilities, as well as any entity that can hold one or more boxes and may need placement itself.
Similarly, a link can be any connection between two boxes, including a computer network link such as a copper, optical fibre, laser, or wireless link, which can itself be used as an Ethernet, FibreChannel, InfiniBand, telephone, wide-area, local-area, campus-area, metropolitan-area, serial, parallel, or other link type. Links can include other types of connections, too, such as pipes (e.g., for cooling fluids, hydraulic lines, or compressed air), cables (for mechanical effects), and so on. To simplify exposition, this document uses computer network components and devices as an exemplar problem domain, but this in no way limits the scope of what is described herein.
One current solution to designing the racking and wiring configurations for networked devices is by manually designing the configurations. In designing the configurations for storage area network (SAN) devices, the above solution can sometimes be facilitated with the use of visualization software such as, for example, various computer-graphics drawing programs. However, this manual-based solution can be extremely time-consuming, suboptimal and error-prone for realistic-sized SANs.
Another current solution to designing the racking and wiring configurations is to use a canned solution structure, such as the “group common components together” approach. However, this solution is also error-prone and typically results in designs that are more expensive than necessary.
Another current solution in designing the racking and wiring configurations is to use existing algorithms for the bin-packing problem, which will ensure that the boxes (e.g., SAN devices, computers, hubs, switches, and/or the like) are loaded into the minimum number of racks. However, this solution disadvantageously disregards the cost and vulnerability of inter-rack wiring (i.e., wiring links that span between racks).
Thus, the current approaches and/or technologies are limited to particular capabilities and/or suffer from various constraints.